A Beauveria phyloggeny inferred from nuclear ITS and EF1-α sequences:: evidence for cryptic diversification and links to Cordyceps teleomorphs
A Beauveria phyloggeny inferred from nuclear ITS and EF1-α sequences:: evidence for cryptic diversification and links to Cordyceps teleomorphs
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DOI：
10.3852/mycologia.97.1.84
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发表时间：
2005-01-01
期刊：
影响因子：
2.8
通讯作者：
Buckley, E
中科院分区：
文献类型：
--
作者：
Rehner, SA;Buckley, E
白僵菌是一种全球分布的土壤传播的昆虫病原菌丝菌属，是昆虫病原学研究和害虫生物防治的模式系统。由于缺乏分类信息的形态学，白僵菌的物种识别是困难的。这阻碍了本属植物物种多样性的评估和对其自然史的研究。采用基因谱系学方法研究了白僵菌和几种推测相关的冬虫夏草种的分子系统发育多样性。对86个来自不同地理来源、不同生境和不同昆虫寄主的样本分离物进行了油核糖体内转录间隔物（ITS）和延伸因子（ef1 - α）序列分析。采用最大简约法和贝叶斯似然法推导了系统发育树。在ef1 - α和联合基因系统发育中解析了白僵菌中6个支持良好的分支，暂时命名为A-F。球孢白僵菌（Beauveria bassiana）是一种普遍存在的物种，其形态特征为球形至亚球形分生孢子，被确定为非单系，由两个不相关的分支a和C组成。进化枝a分布于全球，包括亚洲的远形虫草（Cordyceps staphylinidaecola）及其可能的同义词球孢白僵菌（C. bassiana）。分支B包括布隆氏芽孢杆菌的分离株，这是一种以椭球状分生孢子为特征的欧亚物种复合体。分支D包括B. caledonica和B. vermiconia，它们分别产生圆柱形和逗号形的分生孢子。来自亚洲的Glade E包括变形白僵菌（Beauveria anamorphs）和冬虫夏草（Cordyceps teleomorph），它们都能产生椭圆形的分生孢子。Glade F，豆豆属植物系统发育的基础分支，包括南美种B. amorpha，它产生圆柱形分生孢子。在A、B和C分支中检测到的谱系多样性表明，主流形态物种概念低估了这些群体内的物种多样性，球孢球藻（A和C分支）谱系的大陆地方性表明，距离飞行的隔离是影响这些分支进化多样化的重要因素。排列试验表明，球孢白僵菌A和C支系的寄主关联基本上是随机的，这支持了过去关于该物种不具有寄主特异性的假设。而11枝和D枝的分离株主要以油鞘翅目寄主为主。虽然取样不充分，但这些分支不足以评估较低分类等级的寄主隶属关系。葡萄球菌/球孢虫草和圣甲虫虫草在白僵菌中的系统发育位置证实了这些联系的先前报道。这些结果为进一步研究白僵菌及其相应的冬虫夏草远形菌的分类、系统发育和比较生物学建立了系统发育框架。
Beauveria is a globally distributed genus of soil-borne entomopathogenic hyphomycetes of interest as a model system for the study of entomopathogenesis and the biological Control of pest insects. Species recognition in Beauveria is difficult due to a lack of taxonomically informative morpholopy. This has impeded assessment of species diversity in this genus and investigation of their natural history. A gene-genealogical approach was used to investigate molecular phylogenetic diversity of Beauveria and several presumptively related Cordyceps species. Analyses were based oil nuclear ribosomal internal transcribed spacer (ITS) and elongation factor 1-alpha (EF1-alpha) sequences for 86 exemplar isolates front diverse geographic origins, habitats and insect hosts. Phylogenetic trees were inferred Using maximum parsimony and Bayesian likelihood methods. Six well supported clades within Beauveria, provisionally designated A-F, were resolved in the EF1-alpha and combined gene phylogenies. Beauveria bassiana, a ubiquitous species that is characterized morphologically by globose to subglobose conidia, was determined to be non-monophyletic and consists of two unrelated lineages, clades A and C. Clade A is globally distributed and includes the Asian teleomorph Cordyceps staphylinidaecola and its probable synonym C. bassiana All isolates contained in Clade C are anamorphic and originate from Europe and North America. Clade B includes isolates of B. brongniartii, a Eurasian species complex characterized by ellipsoidal conidia. Clade D includes B. caledonica and B. vermiconia, which produce cylindrical and comma-shaped conidia, respectively. Glade E, from Asia, includes Beauveria anamorphs and it Cordyceps teleomorph that both produce ellipsoidal conidia. Glade F, the basal branch in the Beanveria phylogeny includes the South American species B. amorpha, which produces cylindrical conidia. Lineage diversity detected within clades A, B and C suggests that prevailing morpho logical species concepts underestimate specics diversity within these groups, Continental endemism of lineages in B. bassiana s.l. (clades A and C) indicates that isolation by distance flits been all important Factor ill the (evolutionary diversification of these clades. Permutation tests indicate that host association is essentially random in both B. bassiana s.l, clades A and C, supporting past assumptions that this species is not host specific. In contrast, isolates in clades 11 and D occurred primarily oil coleopteran hosts. although sampling ill these clades was insufficient to assess host affliation at lower taxonomic ranks. The phylogenetic placement of Cordyceps staphylinidaecola/bassiana, and C. scarabaeicola within Beauveria corroborates prior reports of these connections. These results (establish it phylogenetic Framework for further taxonomic, phylogenetic and comparative biological investigations of Beauveria and their corresponding Cordyceps teleomorphs.